A. The POTS Network
The Plain Old Telephone Service (POTS) network, which has been in existence for over 100 years, is well designed and well engineered for the transmission and switching of 3 kHz voice calls. The POTS network is a real-time, low-latency, high reliability, moderate fidelity voice telephony network. It is not designed for, nor especially well suited for, other forms of communications, including wideband speech or audio, images, video, fax, and data. The POTS network is inherently "telephone" or "handset" oriented and is driven by the need of real-time voice telephony.
There are approximately 270 million users of the POTS network in the United States, making POTS access nearly ubiquitous throughout the US. On the other hand, the POTS network has high access costs, and for international calls, settlement costs.
1. Voice and signaling circuits
Today's POTS network includes a plurality of subnetworks. The two primary subnetworks are a circuit-switched voice subnetwork and an out-of-band signaling subnetwork. In addition, the POTS network includes other packet subnetworks used for operations and network management functions.
The POTS circuit-switched voice subnetwork includes voice-grade circuits that can carry voice signals or data at multiples of a basic 64 kilobits/second rate.
The voice subnetwork includes a multiplicity of Service Switching Points (SSP) that are used to set up circuit-switched connections that carry voice traffic or data traffic (i.e., the "payload") on the POTS network. Each SSP may be a switch used by a Local Exchange Carrier (LEC), such as a 5ESS switch (5E) made by Lucent, or a switch used by an InterExchange Carrier (IXC), such as a 4ESS.RTM. switch (4E) made by Lucent.
The POTS signaling subnetwork is itself a packet-switched network, denoted as Signaling System 7 (SS7).
The SS7 signaling subnetwork carries digital information which assists in fast call setup and routing, as well as providing transaction capabilities using remote database interaction. The SS7 signaling subnetwork includes a series of paired components connected to an SSP.
Typically, each of the paired components for the SS7 signaling subnetwork includes one or more Signal Transfer Points (STP) and one or more Service Control Points (SCP). Each STP and SCP provides, respectively, a router and a database used to implement call setup, call routing, call control and the logic (or programs) and related information functions used to provide advanced communications services over the POTS network.
Details of STPs and SCPs, their operation, and how they interact with SSPs are well-understood by those skilled in the art.
The SS7 signaling subnetwork also includes a protocol (which, in turn, includes a series of subprotocols). Thus, for example, under the SS7 protocol, it is possible to automatically transfer information about the calling party to the called party (i.e., the so-called "Caller ID"). Furthermore, e.g., the SS7 signaling subnetwork and protocol interacts with the voice subnetwork so as to enable a query from an SSP in the voice subnetwork to a Service Control Point (SCP) database in the SS7 subnetwork for determining how to route a call, such as a toll-free (e.g., "800") call. Thus, e.g., the SCP can return to the SSP a routing number corresponding to the dialed "800" number. Additional call features or services utilizing the interaction capabilities of the voice and signaling subnetwork of the POTS network are well known.
2. Interactive voice response systems
Using known interactive voice response (IVR) techniques, callers can directly update database records or select specific information for retrieval by, e.g., entering touch-tones or using voice commands. Retrieved textual information can be converted to speech and played over the phone, or sent directly to the caller as a fax document. As a result, customers can access information or place orders at their convenience without waiting for a service representative. Businesses benefit by reducing costs associated with attendants and service representatives and by increasing customer satisfaction.
B. Packet Networks
Packet networks are general-purpose data networks which are not tied to fixed-bandwidth circuits. Instead, they are designed to transmit bits (in the form of a packet of fixed or variable length) only when there are bits to transmit. Packet networks evolved independently of telephone networks for the purpose of moving bursty, non-real-time data among computers and are distinguished by the property that packet communications are routed by address information contained in the data stream itself.
Packet networks are especially well suited for sending stored data of various types, including messages, fax, speech, audio, video and still images, but are not well suited for sending real-time communication signals such as real-time speech, audio, and video signals. Typically, one accesses a packet network through a client program executing on a personal computer (PC), and so packet networks are inherently "PC" oriented, and client/server driven. Packet networks provide access to distributed databases and have excellent search capabilities.
There are approximately 30 million users of packet networks in the US; this number of users is growing rapidly and will continue to do so over the next decade. Today, the Internet (the largest and most renowned of the existing packet networks) connects over 4 million computers in some 140 countries. The Internet is implemented using a large variety of connections between those millions of computers. These interconnected computers can support applications, such as electronic mail and the World Wide Web, which facilitate communications between persons across the U.S. or around the globe.
Among the connections between computers typically found on the Internet are routers. Routers serve to send packets along to their destination by examining packet headers to determine the destination address; routers often send packets to another router closer to the destination.
Access to the Internet may be obtained through a point of presence (POP), typically through a server connected to one of the networks that make up the Internet. A large company or business may establish a POP as its own direct connection to the Internet; individuals or small businesses may typically access the Internet through a service provider which may provide a POP for, potentially, a multitude of individuals and businesses.
The Internet's global and exponential growth is common knowledge today. The recent developments of browsers for World Wide Web interfaces and information navigation software, such as a multitude of Web search engines (such as, e.g., Lycos or Alta Vista), coupled with a continuously growing number of public access providers, are making the Internet a fundamental component of the information age, if not the information super highway itself. Users typically communicate over the Internet using a combination of hardware and software providing interconnectivity that is compatible with the standard, namely Transmission Control Protocol/Internet Protocol (TCP/IP).
Several alternate forms of communication have developed which utilize either the POTS network or packet networks (and sometimes both). For example, facsimile (fax) communication is now a commonplace option for transmitting copies of documents over the POTS network. Electronic messaging (e.g., e-mail) is a growing phenomenon for those who use a packet network, particularly the Internet, for communications. In addition, many companies today are using packet networks, locally or internally within the company, which are modeled in functionality based upon the Internet. These packet networks, denoted "intranets," are typically private networks owned or controlled by the company or corporate user. Packets are moved over intranets using the Internet Protocol (IP), and often the same software used in connection with the Internet (e.g., Web browsers) is also used in connection with intranets. Intranet networks are often established to connect to the Internet through a firewall (i.e., a hardware/software combination designed to restrict unauthorized access to the intranet from the outside world).
As the Internet grows, more organizations are publishing information on a "site" on the World Wide Web (Web site). Furthermore, generally available and excellent search capabilities can locate a particular piece of information quickly from this globally-distributed database.
A World Wide Web site on the Internet typically resides on a computer known as a server, which is accessed through the Internet by a person (or a client) utilizing a computer, such as a PC. A Web site consists of one or more Web pages comprising scripts written in Hyper Text Markup Language (HTML) and typically resides on a server compatible with HyperText Transport Protocol (HTTP, a protocol for interfacing with the Internet). Pages at a Web site are typically accessible and viewed by the person using the PC through software called a Web browser, which typically resides on the person's PC. A Web browser, such as the one by Netscape, interprets Web page HTML scripts to provide a graphical user interface that allows easy access to various services over the Internet. Equivalently, Web sites internal to and locatable over a corporate intranet may be set up and accessed in a like manner using the same or virtually the same software (e.g., a Web browser). Such Web sites internal to a corporate intranet are typically HTTP compatible and addressable using Uniform Resource Locator (URL) techniques, and contain Web pages comprising HTML scripts.
Persons may browse the World Wide Web for virtually any kind of information, including information having content derived from one or more media, such as words, sounds or images. Increasingly, businesses are establishing Web sites as a means of providing information to and attracting potential customers, and Web sites are emerging as a means of transacting business. One may locate a company's Web site by, e.g., using one of a number of existing search engines available over the Internet, or browsing other Web sites containing links to the company's Web site, or entering directly the URL, which represents an address for the Web site. Typically, Web browsing takes place in the context of an interactive communication session, where one may, for example, direct the Web browsing session by choosing to follow hypertext links found in Web sites and/or may respond to information located at various Web sites.
C. Integration of the POTS and Packet Networks
Recently, several new evolutionary systems have emerged with the goal of integrating the POTS and packet networks, including the introduction of packet telephony and "hop-on hop-off" servers.
1. Packet Telephony
An Internet-related development is packet telephony. Packet telephony involves the use of a packet network, such as the Internet, for telecommunicating voice, pictures, moving images and multimedia (e.g., voice and pictures) content. Instead of a pair of telephones connected by switched telephone lines, however, packet telephony typically involves the use of a "packet phone" or "Internet phone" at one or both ends of the telephony link, with the information transferred over a packet network using packet switching and packet routing techniques.
Packet telephony systems were created with the goal of providing real-time speech communications over packet networks. The basic idea of packet telephony is (1) to use the sound board of a multimedia PC to digitize speech into bits; and (2) to use the processor in the computer to compress the bitstream, packetize it, and then send the result over a packet network to another multimedia PC with the same or equivalent functionality. Although the basic idea is feasible, the resulting realtime voice communications experience is of low quality, albeit at low cost. Some of the drawbacks are:
long transmission delays (due to packet size, packet buffering, packet overheads and routing delays) PA1 lost and delayed packets (due to network congestion) PA1 poor quality of the coded voice (due to the use of low complexity speech coders) PA1 difficulty of finding the Internet Protocol (IP) address of the person at the destination PA1 need to call people who did not have access to the packet network
Several improvements in these areas have been made since the initial introduction of packet telephony, and others have been suggested (e.g., reservation protocols such as RSVP).
2. HOHO Servers
As packet telephony grew in popularity, the need to call people who did not have access to the packet network led to the creation of Hop-on Hop-Off (HOHO) servers. The development of Hop-on Hop-Off servers provided a mechanism for PC-initiated telephone calls on a packet network to connect with the POTS network and terminate at a customer's telephone handset or vice-versa. The HOHO or server brings the packet network and POTS network together at a common gateway interface, which bi-directionally converts IP packets into voice and signaling information, such as the sequence of messages used to set up, bridge, and tear down calls. In this way, voice communication is established across the packet and POTS networks.
3. Call Center-based telephony
Another recent development in linking together the POTS and packet networks is the call center-based system developed by Genesys Telecommunications Laboratories, among others. In a typical call center-based scenario, a customer finds a product/service, while browsing the Web, for which more information is desired. If the particular product/service provider maintains both a Web server and a call center, the customer, along with the Web connection, can be linked to a call center representative in the following way. The customer is asked to click on a button on the PC screen which requests customer information (e.g. home telephone number, name, etc.). The Web server passes the information to the database server in the call center system, which initiates a POTS call to the customer and connects the call to a call center representative. At the same time, the Web page that the customer is looking at may be passed to the call center representative, along with side information such as the length of time that the customer has been looking at the page, the previous pages which have been looked at, etc. In this manner, the customer maintains a voice connection to the call center representative, as well as synchronization between what the call center representative sees on the PC screen and what the customer sees on the PC screen.
While the systems described above provide some limited usefulness for individualized applications, none of these systems provide a comprehensive means for combining the POTS network and a packet network (such as the Internet) in a way that takes full advantage of the signaling and real-time signal processing capabilities present in the POTS network. For example, current packet telephony systems do not take advantage of the SS7 signaling subnetwork and protocols to assist call setup and routing. Further, none of the current systems that enable packet telephony using a POTS telephone connection at one or both ends have the capability to intelligently make switching or routing decisions between the POTS network and packet network based upon considerations such as desired quality, time, cost, bandwidth or other considerations.
What is desired is a way to combine the POTS network and a packet network, taking full advantage of the signaling capabilities present in the POTS network as well as the addressing capabilities inherent in a packet network, to seamlessly combine the networks for flexible and optimal communications based upon considerations such as desired quality, time, cost or bandwidth.